WO1981003128A1

WO1981003128A1 - Improved scrubbing apparatus

Info

Publication number: WO1981003128A1
Application number: PCT/US1981/000603
Authority: WO
Inventors: A Stone
Original assignee: A Stone
Priority date: 1980-05-08
Filing date: 1981-05-06
Publication date: 1981-11-12
Also published as: US4289506A; EP0051641A1

Abstract

Methods and apparatus for scrubbing a gas with a scrubbing fluid. The apparatus disclosed includes a rotatable scrubbing fluid impeller (21) rotatable about an axis of rotation and a scrubbing fluid supply conduit (29) to supply scrubbing fluid to an inner portion (21b) of the impeller so that upon rapid rotation of the impeller about the axis the scrubbing fluid is impelled outwardly and forms a rapidly rotating scrubbing fluid curtain of discrete jets at the outer periphery thereof. In one embodiment, the rotatable impeller includes first and second axially displaced sections, the first section for impelling the scrubbing fluid outwardly and the second section for impelling the gas outwardly to and through diffuser vanes, and then to vanes for altering the direction of flow of the gas as it passes from the diffuser exit plenum so that it is forced through the rapidly rotating scrubbing fluid curtain in a direction opposite to that of the rotation of the scrubbing fluid. In another embodiment, the rotatable impeller includes an annular scrubbing fluid distribution surface (21a) including a plurality of discrete scrubbing fluid jet forming elements (23) located at the periphery thereof.

Description

IMPROVED SCRUBBING APPARATUS

TECHNICAL FIELD The present invention is directed to methods and apparatus for scrubbing a gas with a scrubbing fluid. More particularly, the present invention is directed to such methods and apparatus including a rotatable impeller for forming a rapidly rotating curtain of discrete jets of scrubbing fluid at the outer periphery of a rotating impeller, and for forcing the gas to be scrubbed through that curtain.

BACKGROUND ART

While various types of devices have been known for many years for effecting the removal of particulate matter from gases for various purposes , a significant advance in this art is represented by U .S. Patent No. 3 , 596 , 885 , which issued on August 3, 1971. This patent discloses such a device which includes a rotatable impeller (wheel 21 ) which is used to' establish a rapidly rotating curtain of scrubbing fluid at the outer peri¬ phery thereof . Furthermore, this curtain is then utilized to scrub a gas which is directed against that curtain at an acute angle to a plane normal to the axis thereof and opposed to the direction of rotation of the curtain of scrubbing fluid . In U. S. Patent No. 3,596 ,885 this is accomplished by directing the gas from inlet 20 into an annular passage between inner and outer housings 10 and 11 , where the rapidly rotating curtain of scrubbing fluid is located, and by directing the gas stream in the required manner by means of web 28, as shown in Figure 3 thereof.

The apparatus and method disclosed in the ' 885 patent has proven to be extremely valuable from a commercial standpoint. However, the search has continued for improvements in such a system, and the present application discloses a number of improvements which are applicable thereto .

Firstly , in connection with the concept of combining in a single apparatus means for impelling both a gas and a liquid , U. S. Patent No. 3 , 478, 496 to Keough discloses an impeller 40 located at the top of an exhaust stack 10 within enclosure 20. The fan redirects the gas from the stack outwardly within enclosure 20. In addition , however, part of the fan 40 defined by space 68 serves to produce a water jacket within the enclosure 20 as shown. However, contact with gas of any kind does not occur until the water jacket has cascaded downwardly under the force of gravity, and even then there is no passage of the gas through a rapidly rotating curtain of fluid, such as in the manner disclosed in the aforementioned '885 patent. Also, U.S. Patent No. 2 ,590,342 to Niehaus et al discloses an air washer including an impeller fan which rotates at high speed to atomize a stream of washing liquid so as to produce a fog of tiny liquid particles and forces the gas through that fog . In particular, the patentee employs a fan 23 rotating at high speed to atomize washing liquid flowing through perforations 32 and conduit 29 so that the liquid and gas are simultaneously forced outwardly by fan 23 - Again, there is no attempt to pass the gas stream to be scrubbed through a rapidly rotating curtain of scrubbing fluid.

British Patent No. 681 ,609 to Jennings discloses yet another apparatus of this type, in this case for removing fine dust from blast furnace gas . This patentee employs a turbine-like appa¬ ratus including a series of discs 11- for rotation at high speed . Thus , water from feed distributor 19 is carried through holes drilled in collars 13 separating the discs 11 and emerges on the surface of each of the flat discs and spins outwardly therefrom to generate a dense curtain of water for contact with the gas passing therethrough. Again, no apparatus incorporating both a gas and scrubbing liquid impeller for forcing both gas and liquid outwardly is disclosed therein. As for the nature of the scrubbing fluid impeller means itself, various references in a number of fields teach means for creating sprays of liquid and the like. Thus , U .S. 2 , 850 ,232 to Ingram discloses a centrifugal sprayhead, in this case for receiv¬ ing paint, lacquer or other liquids , and to effect uniform distribution around the rotor thereof . In this case atomized particles are said to be produced by means of a sprayhead which includes a rotor body 6 having a central hub 7 so that liquid can be delivered to the hub bore 8. Thus liquid enters aperture 31 from bore 8 and finally through a series of apertures 36, strikes flange 41 so as to engage generally flat, annular surface 43 , the outer periphery of which is bounded by wall 46 and finally to the rotor surface 48 including a plurality of grooves or slots extending over the conical surface thereof. Reference is also made to U. S. Patent No. 3, 765, 688 to Junker, which relates to a fluid seal, but which does include a U-shaped channel member 12 and an annular baffle 18 projecting thereinto, further wherein oil delivered from nozzles 23 into channel member 12 can escape through bleed holes 24-

Additional patents relating to gas seals produced by liquids so as to confine a gas stream include, aside from the Junker patent, U . S. Patent No. 3 ,694, 042 to Rabenhorst , which discloses a liquid sealed in a radial fluid bearing, in this case including an annular member 34 positioned within a rotating annular flange 22 which retains fluid 14 therein through the action of centrifugal force. In addition , U. S. Patent No. 1 ,949, 429 to McGee discloses another type of fluid seal arrange¬ ment.

DISCLOSURE OF INVENT ION

According to the present invention , there is provided appar¬ atus for scrubbing a gas with a scrubbing fluid , comprising rotatable scrubbing fluid impeller means mounted on an axis for rotation thereabout, scrubbing fluid supply means for supplying scrubbing fluid to the inner surface of the scrubbing fluid impeller means so as to form a scrubbing fluid curtain at the outer periphery of the scrubbing fluid impeller means , upon the rapid rotation thereof, and gas redirection means for passing the gas through the scrubbing fluid curtain in a direction opposed thereto so as to scrub the gas with the scrubbing fluid, and including the scrubbing fluid impeller means having an annular scrubbing fluid distribution surface including a plurality of discrete - scrubbing fluid jet forming means located only at the outer peripher of the impeller for interrupting the surface so as to channel the scrubbing fluid into discrete scrubbing fluid jets and to thereby form a rapidly rotating scrubbing fluid curtain

"BUKHAT

OMP1 of discrete jets at the outer periphery of the impeller upon its rapid rotation.

This embodiment of the invention incorporates several over¬ all advantages therein. Thus , and as particularly compared to prior highly successful apparatus such as that of U. S. Patent No. 3,596 ,885 , the present apparatus provides even greater energy savings , primarily because the scrubbing fluid can pass outwardly in an even more unimpeded and efficient manner. Furthermore, the fluid is capable of imparting a significant degree of kinetic energy to the gas , acting in a manner similar to that of a blower. Furthermore, it is possible to employ a scrubbing fluid herein which includes a relatively high degree of solids , or a slurry , in view of the relatively unobstructed flow of fluid. In one embodiment of the invention , a rotatable gas impeller is provided axially displaced from the rotatable scrub¬ bing fluid impeller, and rotatable about a common axis there¬ with. The rotatable gas and scrubbing fluid impellers are located in adjacent, parallel planes , and gas supply means are also included for supplying the gas to be scrubbed to the gas impeller so that upon rapid rotation of both the gas and scrubbing fluid impellers both the gas and the scrubbing fluid are impelled outwardly in their respective parallel planes .

In one embodiment of the invention , fixed diffuser vane means are provided at the outer periphery of rotatable impeller means for substantially reducing the rotational component of the gas , and so as to increase its pressure while reducing its velocity . That is , as the gas is impelled outwardly from the rotatable impeller it will include a radial cvector component and a rotational vector component, which combine to give it a resultant vector therebetween . A plurality of these vanes can be provided, each having an arcuate configuration , and including a first or inlet end and a second or outlet end, with the inlet end being -^"directed substantially coincident with the resultant vector of the flowing gas , and the outlet end being directed so as to impel the gas in a direction which is substantially radially directed , and which is now at an increased static pressure. In one embodiment of the invention , a scrubbing fluid distribution hub is provided adjacent to the axis of rotation of the scrubbing fluid impeller, and a scrubbing fluid conduit terminating a predetermined distance from the scrubbing fluid distribution hub , and scrubbing fluid directing means being mounted on the axis of rotation for directing the scrubbing fluid from the end of the scrubbing fluid conduit to the fluid distribution hub , the scrubbing fluid directing means being spaced from the end of the scrubbing fluid conduit so that the scrubbing fluid directing means is free to rotate with the rotatable impeller without interference from the scrubbing fluid conduit, while at the same time substantially all of the scrub¬ bing fluid passes from the end of the scrubbing fluid conduit to the fluid distribution hub. In another embodiment of this invention , the fluid seal includes a generally axially extending wall extending from the annular scrubbing fluid distribution surface so that scrubbing fluid builds up against that wall as the fluid passes radially outward, this wall member having a substantially L-shape^'d cross-section , including an axially extending leg and ^• an inward¬ ly directed radially extending leg .

According to the method of the present invention , a scrub¬ bing fluid is supplied to a location adjacent to the axis of rotation of a rotatable scrubbing fluid impeller including an annular scrubbing distribution surface so as to project the scrubbing fluid radially outward upon the rapid rotation of the rotatable scrubbing fluid impeller and produce a scrubbing fluid curtain at the outer periphery of the scrubbing fluid impeller, and passing the gas to be scrubbed through the rapidly rotating scrubbing fluid curtain in a direction opposite thereto so as to serve the gas with the scrubbing fluid , and including forming a substantially continuous sheet of scrubbing fluid adjacent to the axis of rotation and for substantially the entire surface of the annular scrubbing fluid distribution surface , and forming the substantially continuous sheet of scrubbing fluid into a plurality of discrete liquid jets at the outer periphery of the annular scrubbing fluid distribution surface so as to form a rapidly rotating scrubbing fluid curtain of discrete jets at the outer

^'Bϋ κ £_-uT periphery of the scrubbing fluid impeller up its required rotation. In one embodiment of the invention the gas is supplied to a location adjacent to the axis of rotation of rotatable gas impeller means , these axes of rotation comprising a common axis , and the locations being axially displaced from each other along that common axis , thus causing the gas and the scrubbing fluid respectively, to pass radially outward from these locations , respectively, in first and second axially displaced planes by rapidly rotating both rotatable impellers about their common axes .

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings , Figure 1 is a side, sec¬ tional, elevational view of a scrubbing apparatus of • the present invention;

Figure 2 is a front, elevational view of one embodiment of the rotatable impeller of the present invention ;

Figure 3 is a side, sectional, elevational view of the apparatus of Figure 2 taken along lines 3-3 thereof;

Figure 4a is a partial, side, sectional view of a portion of one embodiment of the rotatable impeller of the present invention ; Figure 4b is a partial, side, sectional view of a portion of another embodiment of the rotatable impeller of the present inven¬ tion ;

Figure 5 is a partial , side, sectional view of another embodiment of the rotatable impeller of the present invention ; Figure 6 is a partial, side, sectional view of another embodiment of the rotatable impeller of the present invention ;

Figure 7 is a partial , side, sectional view of another embodiment of the rotatable impeller of the present invention ;

Figure 8 is a partial, top perspective view of another embodiment of the rotatable impeller of the present invention;

Figure 9 is a partial, side, sectional, elevational view of a portion of one embodiment . of a combined rotatable impeller including first and second sections in accordance with one embodiment of the present invention ; Figure 10 is a partial , side , sectional , elevational view of a portion of a liquid seal of one embodiment of the rotatable impeller of the present invention ;

OMP1 Figure 11 is a partial, side, sectional, elevational view of a portion of another liquid seal of the present invention ;

Figures 12 and 13 are partial , side, sectional , elevational views, shown together in an exploded manner, of the embodiment of the combined impeller members of the present invention as shown in Figure 9 ;

Figure 14 is a side, sectional, elevational view of another embodiment of the impeller of the present invention ;

Figure 15 is a schematic representation of a combined apparatus in accordance with one embodiment of the present invention ;

Figure 16 is a schematic representation of a combined apparatus in accordance with another embodiment of the present invention ; Figure 17 is a schematic representation of a combined apparatus in accordance with another embodiment of the present invention ;

Figure 18 is a schematic representation of a combined apparatus in accordance with another embodiment of the present invention ; and

Figure 19 is a diagrammatical representation of a portion of the gas impeller and diffuser of the present invention .

BEST MODES OF CARRYING OUT THE INVENTION Referring to the figures , in which like numerals refer to like portions thereof, Figure 1 shows an overall gas scrubbing apparatus 1 of this invention , including a hollow outer housing 2 including an inlet end 3 and an outlet end 5. The hollow outer housing 2 is coaxial with an inner housing 7 , which as shown has conical ends 9 and 11 , thus forming an annular passageway between the inner and outer housings , 7 and 2 , re¬ spectively. The two parts of the inner housing 7 thus provide an annular gap 13 therebetween . Furthermore, the cylindrical wall sections 15 and 17 forming that annular passageway with the outer housing 2, and which form the sides of annular gap 13 , are themselves cylindrical , and are concentric with respect to the cylindrical midportion 19 of outer housing 2.

O PI A rotatable impeller or wheel 21 is mounted in the plane of annular gap 13 between the two halves of inner housing 7, and coaxial and on a common axis with both the inner and outer housings , 7 and 2, respectively. The diameter of the rotatable 5 impeller 21 , is substantially equal to the outer diameter of the cylindrical portions 15 and 17. Shown diagrammatically in Figure 1 is one possible method for rapidly rotating the rotatable impeller means 21 , including a shaft 20, for turning the impeller, which in turn is driven by a motor 8, while supports

10 22 are shown for the shaft bearings, and support 10 is shown for the motor.

Located in the annular passage between the inner and outer housings 7 and 2 are fixed vanes or spaced webs 25 and 27- While these serve to support the inner housing 7 within the

15 outer housing 2, the primary function of vanes 25 is to assure that the gas passing through the annular space between the inner and outer housings impinges upon a curtain of discrete jets of scrubbing fluid generated therein ( as is discussed in more detail below) in a direction generally counter to the direc- 0 tion of travel of the rotating impeller. This phenomenon is discussed in U. S. Patent No. 3,596 ,885 , as is the fact that this increases the impaction thereof so as to achieve increased atomization and resultant entrapment of the particulate matter in the gas by the liquid. On the other hand, vanes 27 are intended 5 to establish a distinct flow pattern for the gas as it is . discharged from the housing . In any event, the general con¬ struction of these vanes 25 and 27 is shown in more detail in Figure 3 of U.S. Patent No. 3 ,596 , 885 , which figure and descrip¬ tion thereof is incorporated herein by reference thereto. 0 Turning now to the configuration of the rotatable impeller

21 itself, which forms a significant element in the embodiment of the present invention shown in Figure 1 , the impeller 21 has a circular configuration and has a substantially open face, i. e. , as compared to the individual pipes or tubes employed in the 5 '885 patent. Impeller 21 can preferably be substantially planar, or it can include a substantially conical portion as is shown more clearly in Figure 14. The upper face 21a of impeller 21 includes a central well portion 21b , which is surrounded by an

O annular sloping portion 21c, leading to the upper surface 21a thereof. The annular well portion 21b thus surrounds the central axis of rotation of the impeller. Water or other scrubbing fluid which is to be supplied to the impeller 21 is thus initially directed to well portion 21b so that it initially enters the center of the impeller 21 at a point below or depressed from the upper, preferably planar surface 21a. As is discussed in more detail below, this assists in retaining the fluid on the surface of the impeller 21. The upper portion of the impeller face 21a will preferably be substantially flat or planar, or again as shown in Figure 14, can have a substantially conical face , e.g . , one having an occluded angle α , generally between about 120 and 175 ♦ Further, this inner portion of the impeller surface is preferably not interrupted by any projections , etc. , which would interfere with the flow of scrubbing fluid, and/or which would prevent the formation of a substantially continuous sheet of fluid over that surface. At the outer periphery 21d of the impeller, however, there are located discrete liquid jet forming members 23 , various types of which are shown in Figures 4-8. These members 23 , are intended to convert the substantially continuous scrubbing fluid sheet on the surface of the impeller into a plurality of discrete liquid jets , which themselves then form a rapidly rotating scrubbing fluid curtain of discrete jets at the outer periphery of the impeller, i. e. within the space between the inner and outer housings 7 and 1. The members 23 themselves may be directed coincident with a radius 26 of the impeller 21 , be disposed at an angle θ of between 0 and 60 with respect thereto, or in some cases may be disposed at an angle 3 of between 0 and 15 with respect thereto, i. e . , where θ is measured in the direction of rotation of the impeller as shown by the arrow in Figure 2 , and is measured counter to that direction of rotation . It is most preferred, however, for these elements 23 to be disposed at an angle θ , and most preferably where "θ -is approximately 0 , i. e. , where the elements are radial. Elements 23 must be of a nature so as to produce discrete fluid jets at the outer periphery of the impeller. They may, how¬ ever, be formed from the impeller itself, as shown in Figures .a, 4b , and 7 , or built up on the surface of the impeller, as shown in Figures 5, 6 and 8. The particular embodiments shown thus include a sloping surface 65, as shown in Figures 2, 3 and 4b, forming a plurality of grooves around the periphery of the impeller. Also shown in Figure 4a are rectangular notches 67 and in Figure 5, a continuous upstanding annular wall portion 68, including inwardly directed annular lip 70 forming a trough , 71 , in which fluid may collect, and then form into jets by passing through a plurality of orifices 72, which can include a cylindrical portion 73 and a circular tapered inlet 74 coaxial therewith. Figure 6 shows another embodiment of these jet forming elements 23, in this case, as viewed from the outer periphery of the impeller towards its axis of rotation , including a series of upstanding blocks 75 formed at that periphery , including upstanding walls 76 and upper and lower cross mem- bers, 77 and 78, respectively , mounted upon a circular base plate 82. Figure 7 shows a similar embodiment, but in this case a series of teeth 79 are produced at the periphery thereof, each including sloping surfaces 80. Finally, Figure 8 shows yet another such embodiment, in this case where a series of sloping ramp members 81 are affixed to the impeller itself, again including a circular base plate 82 , which is particularly impor¬ tant in this case so that openings are not left through the entire face of the impeller itself. Thus , V-shaped notches can be formed at the periphery and folded up along one side 83 thereof . The scrubbing fluid can be supplied to the well portion

21b of the impeller 21 by means of the apparatus shown in Figure 1. This includes an open-ended cylindrical scrubbing fluid directing member 31 circumferentially placed around the axis of the impeller 21 , and including inwardly directed annular lip 24. This entire scrubbing fluid directing member 31 is in turn mounted on the axis by means of struts 28. In this manner, scrubbing fluid enters through conduit 29, which terminates at the opening formed by inwardly directed lip 24 , as shown in Figures -1 and 3, and is retained within the fluid directing member 31 and directed onto the surface of the impeller at the well portion 21b. From there the fluid is projected outwardly by the centrifugal force created by the rapid rotation of impeller 21 without leaving the surface of the impeller. It is thus important _s ' A -< r. O PI that the end 26 of fluid directing member 31 extend to a point below the planar surface 21a of impeller 21 , as is specifically shown in Figure 3.

In connection with the operation of the embodiment shown in Figure 1 , the gas which is to be cleaned enters inlet 3 of the outer housing 2, generally under the influence of a blower, fan or other means , and is forced to pass between inner and outer housings 7 and 2, through the annular passage discussed above. At the same time, scrubbing fluid is fed through conduit 29 and is expelled from the end of conduit 29 at a point near the axis of rotation of impeller 21. This fluid is thus directed by means of the fluid directing member 31 and its inwardly extending lip 24 into the well portion 21b of impeller 21 , at a point below its upper surface 21a . The impeller 21 rotates rapidly , e. g . , at the speeds at the outer periphery of from 80 to 100 ft/sec. and upward, to much greater speeds , and this high speed forms a rapidly rotating curtain of scrubbing fluid, which is thrown outwardly to form a substantially continuous sheet of scrubbing fluid on the flat upper surface 21a of impeller 21 . As the scrubbing fluid passes outwardly, and when it reaches the outer periphery of impeller 21 , it is formed into a plurality of discrete scrubbing fluid jets by means of members 23 , so as to produce a rapidly rotating scrubbing fluid curtain of discrete jets within the annular passage between inner and outer hous- ings 7 and 2, respectively. As is also set forth above, fixed vanes 25 redirect the gas flow so that it is directed against the direction in which the impeller is rotating , and thus the impacting of the scrubbing fluid and the gas stream results in atomization of the liquid and ultimate p articulate collection . The major portion of the scrubbing fluid, now containing particulate matter cleansed from the gas , can now be drained out of the device through drain 36 ' , which is tangential to the impeller and oriented with respect to the rotational direction of the impeller to assist in the discharge thereof. The cleaned or scrubbed gas continues on through the annular passage , this time redirected by vanes 27 , which are oriented in the direction of the scrubbing fluid , and finally through outlet 5 for further demisting where desired.

i ^0MPI In the scrubbing fluid impeller 21 shown in Figure 14, as noted above, the base 21a thereof is conical in configuration , and the angle α is from about 120 to 175 • Furthermore, in this embodiment the scrubbing fluid directing member 31a employed is not cylindrical, as is the open-ended cylindrical scrubbing fluid directing member 31 in Figures 1 and 3, but is a truncated right circular conical section with its larger diameter located adjacent to the impeller surface . Further, this end 31b of the scrubbing fluid directing member 31a, is located beneath a plane established by connecting together the elevated ends or periphery of the impeller 21 itself, again in order to insure that the scrubbing fluid will remain on the surface of the impeller during its rotation, and held in place by stays 28a.

As is discussed above in the embodiment shown in Figure 1 , as well as in the apparatus shown in U .S. Patent No. 3,596 , 885 , it is generally necessary to supply the gas to inlet 3 with the assistance or under the influence of a blower, fan or other means for accelerating the gas stream therethrough. In the embodiment shown in Figure 9, however, the impeller is combined with a blower, and both functions , namely generation of a rapidly rotating curtain of discrete jets scrubbing fluid, and acceleration of the gas stream through that curtain , are effected by a single apparatus . Referring specifically to Figures 9 , 12 and 13, a portion of an overall apparatus such as that of Figure 1 is shown. The impeller 32 in this case , however, includes two sections (Figure 13) , namely a scrubbing fluid impeller section 34, which is in many respects similar or equivalent to impeller 21 in Figure 1 , and a gas impeller section 36 axially displaced therefrom. In the embodiment shown in Figure 9 , there is no need for inner and outer housings 7 and 2 to be employed precisely as shown in Figure 1 in order to establish a location for gas scrubbing therein. In this case, by employing combined gas and scrubbing fluid impeller means , the configuration of housing 40 is such as to produce scrubbing in the annular space between the outer wall 41 of housing 40 and the outer periphery of the scrubbing liquid impeller 32. Within that area fixed vanes 25 and 27 are again established, with vanes 25 insuring that the direction of flow of the gas is against or counter to that of the direction of rotation of the scrubbing liquid impeller, so as to direct the gas against the oncoming liquid stream as is dis¬ cussed above, and with vanes 27 insuring that the direction of 5. flow of the gas is concurrent with that of the scrubbing fluid at the point of discharge.

The gas impeller member 36 shown in Figure 9 can also be seen in Figure 13- Both the gas and scrubbing liquid impeller sections are attached to a common hub 4 which in turn is 0 affixed to shaft 20. The liquid impeller section 32 is affixed to the blades of the gas impeller member 36 for rotation therewith. Axially displaced therefrom, and also affixed to hub 4 for rotation therewith is circular rear wall member 43 - The gas impeller member or section of the impeller thus acts as a blower 5 for gas entering the central portion, shown in Figure 9 , and for being forced centrifugally outward therefrom. At the peripheral section of the gas impeller section 36 are located fixed diffuser vanes , 45. The purpose of these diffuser vanes 45 is to alter the direction of flow of the gas to be scrubbed, which has now 0 been accelerated outwardly by the centrifugal force imparted by the rotation of gas impeller member 36. In particular, these fixed diffuser vanes 45 are oriented so as to substantially reduce the rotational component of that flowing gas stream while , and to act as a diffuser for the gas , i.e. to increase its static 5 pressure while reducing its velocity . In particular, this can be accomplished by establishing these diffuser vanes in a manner such as is shown in Figure 19. That is , the diffuser vanes 45 are themselves arcuate in configuration , and their inner or inlet end 45a is oriented in a direction which is coincident with the 0 resultant vector b of the rotational component a and the radial component c of the flowing gas , induced by rotation of the gas impeller 36 in the direction of rotation as shown by the arrow therein. Further, their outer or outlet end 45b are thus substan¬ tially "radial, or may face in a direction opposed to that of the 5 impeller ' s rotation , and the direction of the gas is thus altered so as to exit from the impeller in that direction . The gas stream can now not only exit from the periphery of the gas impeller section in a substantially radial direction , but also at a higher pressure and at a lower velocity. The direction of flow of this gas stream is now diverted into diffuser exit plenum 47 and along 'the outer wall of housing 40 so as to pass through vanes 25 and 27. This gas stream thus passes through the rapidly rotating scrubbing fluid curtain which has been established at the outer periphery of the scrubbing fluid impeller section 32. After passage therethrough, the scrubbed gas stream can exit housing 40 through outlet 50 extending outward tangentially from housing 40 in concert with the direction of rotation of the gas. The supply of scrubbing fluid to the planar face 34 of scrubbing fluid impeller section 32 shown in Figure 9, will now be explained in more detail, with specific reference to Figures 9 and 11. As is shown in Figure 9 , gas entering through an inlet section is generally directed between fixed inner wall section 51 of housing 40, producing a cylindrical duct inlet member as shown in Figures 9 and 11 , the inner end of wall member 51 includes radial outwardly extending annular lip member 52. Scrubbing fluid is delivered to the inner side of this annular lip member 52 by means of scrubbing - fluid conduit supply member 29. This can be accomplished in several ways , including bypassing directly through the lip member 52, or shown in Figures 9 and 10 , or by being directed to the inner face of wall member 51 , as shown in Figure 11.

In the embodiment shown in Figure 11 , a radially recessed well 54 is formed by the surface of scrubbing fluid impeller section 32 and radial inwardly projecting arm 54a . It is essential for this arm 54a to extend to a point radially inward from the outer end of radial projecting lip member 52 , so that when scrubbing fluid is supplied through conduit 29 and passes outwardly well 54 is filled with fluid, and lip member 52 becomes immersed in that fluid. This creates the aforementioned fluid seal between the gas inlet and the interior of housing 40 so that the gas to be scrubbed cannot pass directly to outlet 50 and bypass the gas impeller section 36. In addition , the overflowing fluid from well 54 overflows arm 54a and passes outwardly over the sloping surface 32b of the rotatable liquid impeller 32. Thus , the same fluid which creates the fluid seal also establishes the rapidly rotating curtain of discrete jets of scrubbing fluid at the outer periphery of impeller 32.

-^•§1) ! O Yet another different combined scrubbing fluid delivery and fluid seal mechanism, in this case for the apparatus of Figure 9, is shown in detail in Figure 10. In this embodiment, a baffle member 57 projects linearly and at an angle from a point within well portion 32b of scrubbing fluid impeller 32. In this case, scrubbing fluid conduit 29 is connected directly to the radial outwardly extending lip 52 of annular wall member 51 so that the scrubbing fluid passes therethrough , as is shown by the arrows in Figure 10. It is essential in this case that the inwardly extending baffle 57 terminate at a point radially inward as compared to the outwardly extending lip 52 , again so that the end of lip portion 52 remains immersed in scrubbing fluid during use, and that upon rapid rotation of the rotatable scrubbing fluid impeller, scrubbing fluid is maintained between baffle 57 and wall 37 so as to form the liquid seal discussed above. Furthermore, the overflowing scrubbing fluid again passes through the inwardly projecting end of baffle 57 , as shown by the arrows therein. In this embodiment, a fluid directing channel is established by means of conduit 59 fixed to the outer surface of baffle 57 to direct the scrubbing fluid to a point within the well portion 32b of impeller 32 , so that it can then pass upwardly to surface 32a of impeller 32.

As is also shown in Figure 10 , a bleed conduit 59a is con¬ nected to baffle 57 to provide an outlet for removing suspended matter contained in the scrubbing fluid being fed through line 29 which gravitates to this zone under the influence of the centrifugal forces created therein by permitting a small fraction of the scrubbing fluid fed to be bled therefrom.

Referring next to Figure 18, another embodiment of a com- bined gas and fluid impeller similar to that of Figure 9 is shown schematically . Here, however, the gas inlet is located on the left of the Figure, and the gas passes through the apparatus without it being necessary to reverse its flow , as is the case in Figure^" 9. It is therefore also unnecessary to include the fluid seal arrangements of Figures 9-11 , and a fluid delivery system similar to that in Figure 1 can now be utilized. It is , however, specifically adapted in this case to accommodate the extension of shaft 20 therethrough. Referring next to Figures 15-17 , several embodiments employ¬ ing more than one of the combined rotatable gas/scrubbing fluid impellers , as shown for example in Figure 9, are employed. In Figure 15, for example, a pair of combined gas/scrubbing fluid impellers are placed in a back-to-back relationship along a common axis 60. Thus , in this case, gas can enter through two inlets 51 on either side of hubs 4, pass outwardly under the influence of gas impeller sections 36, through the respective scrubbing fluid curtains established by rapidly rotating scrub- bing fluid impeller sections 32 , and outward into housings 40 and, finally, through exits 50. In the embodiment shown in Figure 16, although similar to that in Figure 15, in this case, the common fixed wall member 62 shown in Figure 15 has been eliminated, except the extent members 62a are required to hold diffuser vanes 45 in place , and a rotating circular rear wall member 43 is shared commonly by the two gas impellers 36a, and a single fixed diffuser vane support member 62a is new employed to support the diffuser vanes 45 and to maintain the division of gas flow therein. - In the embodiment shown in Figure 17, the pair of com¬ bined fluid and gas impellers are separated along common axis 60. In this case, the scrubbing fluid impellers 32a are arranged in a face to face relationship with respect to each other, and each in turn is arranged in a back-to-back relationship with respect to a pair of gas impellers 36a . The scrubbing fluid thus enters through conduit 29 , is separated into arms 29a , and is directed towards the two facing impellers 32b. The gas , however, enters through inlets 51 on either side, is impelled outwardly by gas impellers 36b , and again pass through the rapidly rotating curtain of discrete jets of scrubbing fluid maintained between vanes 25 and 27. The scrubbed gas then exit through a common central outlet 50.

INDUSTRIAL APPLICABILITY

The present invention can be used for scrubbing exhaust and other gases before they are released to the atmosphere. It finds much wider application , however, in that it can be

OMPI modified to scrub gas streams so as to remove various particu- late and other materials from them in a number of environments , including industrial flue gases , auto exhausts , etc .

Claims

WHAT IS CLAIMED IS:

1. Apparatus for scrubbing a gas with a scrubbing fluid comprising rotatable scrubbing fluid impeller means mounted on an axis for rotation thereabout, scrubbing fluid supply means for supplying scrubbing fluid to the inner surface of said scrubbing fluid impeller means so as to produce a scrubbing fluid curtain at the outer periphery of said scrubbing fluid impeller means upon the rapid rotation of said rotatable scrub¬ bing fluid impeller means, and gas redirection means for passing said gas to be scrubbed through said scrubbing fluid curtain in a direction opposed thereto so as to scrub said gas with said scrubbing fluid, characterized in that said scrubbing fluid impeller means (21 , 32 ) comprises an annular scrubbing fluid distribution surface (21a) , and a plurality of discrete scrubbing fluid jet forming means (23 ) located on said surface (21a) only at the outer periphery (21d) of said scrubbing fluid impeller means (21 , 32 ) so as to channel said scrubbing fluid into discrete scrubbing fluid jets and to form a rapidly rotating scrubbing fluid curtain of discrete jets at the outer periphery (21d) of said annular scrubbing fluid distribution surface (21a ) upon the rapid rotation of said rotatable scrubbing fluid impeller means (21, 32 ) .

2. Apparatus as claimed in Claim 1 , further characterized by a rotatable gas impeller means (36) axially displaced from said rotatable scrubbing fluid impeller means and rotatable about a common axis (20) therewith, said rotatable gas (36) and scrubbing (21 , 32 ) fluid impeller means being located in parallel planes, and gas supply means (51 ) for supplying said gas to be scrubbed to said rotatable gas impeller means so that upon rapid rotation of said rotatable gas and scrubbing fluid impeller means about said common axis , both said scrubbing fluid and said gas are impelled outwardly therefrom in said parallel planes.

3. Apparatus as claimed in Claim 1 , characterized in that said scrubbing fluid supply means includes a scrubbing fluid distribution hub (21b ) located adjacent to said axis of rotation of said scrubbing fluid impeller means , a scrubbing fluid conduit (29) terminating a predetermined distance from said scrubbing fluid distribution hub, and scrubbing fluid directing means (3D mounted on said axis for directing said scrubbing fluid from the end of said scrubbing fluid conduit to said fluid distribution hub, said scrubbing fluid directing means (3D being spaced from said end of said scrubbing fluid conduit so that said scrubbing fluid directing means is free to rotate with said rotatable scrubbing fluid impeller means without interference from said scrubbing fluid conduit, while at the same time substantially all of said scrubbing fluid passes from the end of said scrubbing fluid conduit to said fluid distribution hub.

4. Apparatus as claimed in Claim 2, characterized in that said gas redirection means includes diffuser vane means (45) located at the outer periphery of said rotatable gas impeller means (36) for substantially reducing the rotational component of said gas.

5- Apparatus as claimed in Claim 4, characterized in that said diffuser vane means (45) comprises a plurality of diffuser vanes (45) , said diffuser vanes being arcuate and including a first end and a second end, said first end being located radially inward with respect to said second end, said first end of said diffuser vanes being substantially coincident with the resultant vector of the radial and rotational vectors of said gas as it is impelled outwardly from said rotatable gas impeller means , and said second end of said diffuser vanes being directed so that said gas is impelled outwardly from said rotatable gas impeller means at a lower velocity in a substan¬ tially radial direction , and at an increased static pressure.

6. Apparatus as claimed in Claim 2 , characterized in that said gas supply means (5D passes through said rotatable scrubbing fluid impeller means (21 , 32 ) , and including fluid seal means (52 , 59) for providing a fluid seal between said gas supply means (51 ) and said rotatable scrubbing fluid impeller means to prevent said gas from bypassing said rotatable gas impeller means .

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7. Apparatus as claimed in Claim 6, characterized in that said scrubbing fluid supply means comprises a scrubbing fluid conduit (29) located adjacent to said axis of rotation of said rotatable scrubbing fluid^' impeller means, and wherein said fluid seal means (52 , 59) is also located adjacent to said axis of rotation of said rotatable scrubbing fluid impeller means , so that said scrubbing fluid conduit (29) feeds _. said scrubbing fluid to said fluid seal means (52 , 59) prior to its supply to said rotatable . scrubbing fluid means , whereby said scrubbing fluid comprises the fluid to establish said liquid seal and wherein said scrubbing fluid supply means is located radially inward from said fluid seal means..

8. Apparatus as claimed in Claim 1, characterized in that said annular scrubbing fluid distribution surface (21a) includes a central annular well portion (21b ) disposed below said scrub¬ bing fluid distribution surface , so that said scrubbing fluid must move upwardly out of said central annular well portion onto said scrubbing fluid distribution surface as it passes outwardly from said rotatable scrubbing fluid impeller means .

9. Apparatus as claimed in Claim 1 , further characterized by an outer housing ( 1 ) , and an inner housing (7) mounted concentrically with said outer housing so as to form an annular passage therebetween, said rotatable scrubbing fluid impeller means being located within said inner housing , said inner housing including an annular aperture ( 13 ) to permit said rapidly rotating scrubbing fluid curtain to pass freely from said inner housing and into said annular passage.

10. Apparatus as claimed in ^'Claim 1 , characterized in that said annular scrubbing fluid distribution surface is substan- tially jplanar.

11. Apparatus as claimed in Claim 1 , characterized in that said annular scrubbing fluid distribution surface includes a substantially conical portion .

* yK 12. A method for scrubbing a gas with a scrubbing fluid , comprising supplying said scrubbing fluid to a location adjacent to the axis of rotation of rotatable scrubbing fluid impeller means, rotatable scrubbing fluid impeller means having an annular scrubbing fluid distribution surface to project said scrubbing fluid radially outward upon the rapid rotation of said rotatable scrubbing fluid impeller means and produce a scrub¬ bing fluid curtain at the outer periphery of said scrubbing fluid impeller means , and including the step of passing said gas to be scrubbed through said rapidly rotating scrubbing fluid curtain in a direction opposite thereto so as to scrub said gas with said scrubbing fluid, characterized by the steps of forming a substantially continuous sheet of said scrubbing fluid adjacent to said axis of rotation (20) along substantially the entire suface of said annular scrubbing fluid distribution surface (21a) , and forming said substantially continuous sheet of said scrubbing fluid into a plurality of discrete scrubbing fluid jets at the outer periphery (23) of said annular scrubbing fluid distribution surface (21a) so as to form a rapidly rotating scrubbing fluid curtain of discrete jets at the outer periphery of said annular scrubbing fluid distribution surface upon the rapid rotation of said rotatable scrubbing fluid impeller means.

^• 13. The method as claimed in Claim 12 , further character¬ ized by the step of supplying said gas to a location adjacent to the axis of rotation (20) of rotatable gas impeller means (36) , said axes of rotation of said rotatable gas and scrubbing fluid impeller means comprising a common axis (21 ) , and said loca¬ tions being axially displaced from each other along said common axis , thereby causing said gas and said scrubbing fluid to pass radially outward from said locations , respectively, in first and second axially displaced planes by rapidly rotating both said rotatable gas and scrubbing fluid impeller means about said common axis of rotation (21 ) .

14. The method as claimed in Claim 13, further character- ized by the step of altering the direction of flow of said gas as it flows radially outward from said rotatable gas impeller means so that said gas is directed from said first plane to cross said second plane and pass through said rapidly rotating scrubbing fluid curtain of discrete jets .

15. The method as claimed in Claim 14, further character- ized by the step of altering the direction of flow of said gas as it flows radially outward from said gas impeller means in a manner so as to substantially reduce the rotational component of said flow of gas caused by the rapid rotation of said gas impeller means and to act as a diffuser for said gas .

16. The method as claimed in Claim 13, further character¬ ized by the step of first passing said gas through said location adjacent to the axis of rotation of said rotatable scrubbing fluid impeller means , and including providing a fluid seal between said rotatable scrubbing fluid impeller means and said gas passing through said location so as to prevent said gas from bypassing said location adjacent to the axis of rotation of said rotatable gas impeller means.

17. The method as claimed in Claim 16 , further character¬ ized by the step of employing said scrubbing fluid passing radially outward from said location adjacent to the axis of rotation of said rotatable scrubbing fluid impeller means to provide said fluid seal.

OMP